Add Shadcn

Quick Start

The shadcn/ui initialization supports custom themes via a URL parameter.

Compatibility: This skill works with both standard Next.js projects and projects using --no-src-dir. The component paths (components/) automatically adapt to your project structure.

Use this command

bunx shadcn@latest create $(jq -r .name package.json) --preset "https://ui.shadcn.com/init?base=base&baseColor=gray&theme=emerald&iconLibrary=phosphor&radius=none&style=maia&font=nunito-sans&menuAccent=subtle&menuColor=default&template=next" --template next

After initialization, auto-fix formatting and lint issues in generated components:

bunx biome format --write . && bunx biome check --fix .

Note: The format step fixes whitespace/style, and the check --fix step fixes import sorting (organizeImports) in shadcn-generated files. Both are required — shadcn components ship with unsorted imports that fail biome check.

Remove Demo Component

The shadcn preset includes a demo component-example.tsx file. Remove it:

rm -f src/components/component-example.tsx components/component-example.tsx

Update globals.css

After initialization, add the following to app/globals.css (or src/app/globals.css) inside the @layer base block, or as a top-level rule:

html {
  @apply h-dvh overscroll-none;
}

This ensures the app fills the dynamic viewport height on mobile and prevents overscroll bounce effects.

Enforce Monochrome Dark Mode Grays (Required)

After initialization, always post-process the .dark theme block in globals.css to remove chroma from all neutral gray variables. shadcn themes sometimes generate dark grays with blue or purple tint (non-zero chroma in oklch). Mixing these tinted grays with components that use pure neutrals (e.g., React Flow, canvas elements, third-party widgets) creates an ugly warm/cold mismatch.

Rule: Every oklch color in the .dark {} block that represents a neutral gray (background, card, popover, muted, accent, secondary, sidebar, ring, foreground) must have chroma set to 0. Only accent colors like --primary, --destructive, and --chart-* should retain chroma.

For example, if shadcn generates:

.dark {
  --background: oklch(0.13 0.028 261.692);
  --card: oklch(0.21 0.034 264.665);
  --muted: oklch(0.278 0.033 256.848);
  --muted-foreground: oklch(0.707 0.022 261.325);
}

Post-process to:

.dark {
  --background: oklch(0.13 0 0);
  --card: oklch(0.18 0 0);
  --muted: oklch(0.22 0 0);
  --muted-foreground: oklch(0.65 0 0);
}

Variables to make monochrome (chroma=0, hue=0): --background, --foreground, --card, --card-foreground, --popover, --popover-foreground, --secondary, --secondary-foreground, --muted, --muted-foreground, --accent, --accent-foreground, --border, --input, --ring, --sidebar, --sidebar-foreground, --sidebar-accent, --sidebar-accent-foreground

Variables to keep as-is (retain generated chroma): --primary, --primary-foreground, --destructive, --chart-1 through --chart-5, --sidebar-primary, --sidebar-primary-foreground

After initialization, if an AGENTS.md file exists at the project root, verify it documents the Base UI and Phosphor icon conventions. The create-next skill creates this file with the correct conventions.

Multi-Registry Configuration

shadcn/ui supports multiple component registries beyond the official library. This enables access to specialized components from third-party sources.

Recommended Registries

React Bits - Animated and interactive components

• URL: https://reactbits.dev/
• Installation: npx shadcn add @react-bits/<component>

ElevenLabs UI - Agent and audio components

• URL: https://ui.elevenlabs.io/
• Installation: npx shadcn add @elevenlabs-ui/<component>

MapCN - Map components built on MapLibre

• URL: https://mapcn.dev/
• Installation: npx shadcn add @mapcn/<component>

Configure Custom Registries

After running shadcn init, your components.json file supports namespace-based registries. Add custom registries to the configuration:

{
  "$schema": "https://ui.shadcn.com/schema.json",
  "style": "base-maia",
  "registries": {
    "@react-bits": {
      "url": "https://reactbits.dev"
    },
    "@elevenlabs-ui": {
      "url": "https://ui.elevenlabs.io"
    },
    "@mapcn": {
      "url": "https://mapcn.dev"
    }
  }
}

Note: Most community registries work without explicit configuration - the CLI discovers them automatically. The registries section is only needed for private or custom registries.

Using Components from Different Registries

# Official shadcn components
bunx shadcn@latest add button

# React Bits - animated components
bunx shadcn@latest add @react-bits/animated-card

# ElevenLabs - audio player
bunx shadcn@latest add @elevenlabs-ui/audio-player

# MapCN - interactive maps
bunx shadcn@latest add @mapcn/map-viewer

MCP Server for Natural Language Component Discovery

The shadcn MCP server enables AI-assisted component discovery and installation using natural language.

Setup:

# Install shadcn MCP server (if using Claude Code or compatible IDE)
# Configuration is typically added to your MCP settings

Usage: Ask your AI assistant to find and install components:

• "Find me a login form from the shadcn registry"
• "Install an animated card component from React Bits"
• "Add a map component for displaying locations"

The MCP server works with:

• Official shadcn/ui registry
• Third-party component libraries (React Bits, ElevenLabs UI, MapCN, etc.)
• Private company registries (requires authentication via .env.local)

Dark Mode Setup (Required)

After running the shadcn init command, dark mode requires additional setup.

1. Install Dependencies

bun add next-themes

2. Create ThemeProvider Component

Create components/theme-provider.tsx:

"use client";

import { ThemeProvider as NextThemesProvider } from "next-themes";

type ThemeProviderProps = React.ComponentProps<typeof NextThemesProvider>;

export function ThemeProvider({ children, ...props }: ThemeProviderProps) {
  return <NextThemesProvider {...props}>{children}</NextThemesProvider>;
}

3. Create ModeToggle Component

Note: The preset includes the dropdown-menu component, so no additional installation is needed.

Create components/mode-toggle.tsx:

"use client";

import { Moon, Sun } from "@phosphor-icons/react";
import { useTheme } from "next-themes";
import {
  DropdownMenu,
  DropdownMenuContent,
  DropdownMenuItem,
  DropdownMenuTrigger,
} from "@/components/ui/dropdown-menu";

export function ModeToggle() {
  const { setTheme } = useTheme();

  return (
    <DropdownMenu>
      <DropdownMenuTrigger className="inline-flex items-center justify-center gap-2 whitespace-nowrap rounded-md text-sm font-medium ring-offset-background transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring focus-visible:ring-offset-2 disabled:pointer-events-none disabled:opacity-50 border border-input bg-background hover:bg-accent hover:text-accent-foreground h-10 w-10 shrink-0 cursor-pointer">
        <Sun size={20} className="scale-100 rotate-0 transition-transform dark:scale-0 dark:-rotate-90" />
        <Moon size={20} className="absolute scale-0 rotate-90 transition-transform dark:scale-100 dark:rotate-0" />
        <span className="sr-only">Toggle theme</span>
      </DropdownMenuTrigger>
      <DropdownMenuContent align="end">
        <DropdownMenuItem => setTheme("light")}>
          Light
        </DropdownMenuItem>
        <DropdownMenuItem => setTheme("dark")}>
          Dark
        </DropdownMenuItem>
        <DropdownMenuItem => setTheme("system")}>
          System
        </DropdownMenuItem>
      </DropdownMenuContent>
    </DropdownMenu>
  );
}

4. Update Root Layout

Update app/layout.tsx (or src/app/layout.tsx):

import { Nunito_Sans } from "next/font/google";
import { ThemeProvider } from "@/components/theme-provider";

const nunitoSans = Nunito_Sans({ variable: "--font-sans" });

export default function RootLayout({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en" suppressHydrationWarning className={nunitoSans.variable}>
      <body className="font-sans antialiased">
        <ThemeProvider
          attribute="class"
          defaultTheme="system"
          enableSystem
          disableTransitionOnChange
        >
          {children}
        </ThemeProvider>
      </body>
    </html>
  );
}

Font setup: The shadcn preset uses Nunito Sans with the --font-sans CSS variable, which is referenced by the @theme inline block in globals.css. The font-sans Tailwind utility then uses this variable.

5. Use the ModeToggle Component

The ModeToggle component is now ready to use anywhere in your app. Example usage in a page:

Update app/page.tsx:

import { ModeToggle } from "@/components/mode-toggle";

export default function Home() {
  return (
    <div className="flex min-h-screen items-center justify-center bg-background">
      <div className="text-center">
        <h1 className="text-4xl font-bold text-foreground mb-4">
          Dark Mode Setup Complete
        </h1>
        <p className="text-muted-foreground mb-8">
          Click the button below to toggle themes
        </p>
        <ModeToggle />
      </div>
    </div>
  );
}

Critical Requirements

Prevent Flash of Unstyled Content (FOUC)

• Always add suppressHydrationWarning to the <html> tag
• Use disableTransitionOnChange to prevent jarring transitions
• Use defaultTheme="system" to respect OS preference

Use Semantic Color Classes

DO NOT use hardcoded colors like:

• bg-white, bg-zinc-50, text-zinc-900, border-zinc-200

DO use semantic colors:

• bg-background, bg-muted, text-foreground, border-border

Tailwind CSS v4 Canonical Classes

This skill uses Tailwind CSS v4. Some class names have changed from v3:

Always use canonical v4 class names to avoid linter warnings.

Color Token Reference

Common Patterns

Hero section:

<section className="bg-linear-to-b from-muted/50 to-background">

Cards:

<div className="bg-card border border-border rounded-xl">

Text:

<h1 className="text-foreground">Title</h1>
<p className="text-muted-foreground">Description</p>

Buttons:

<button className="bg-primary text-primary-foreground hover:bg-primary/90">

Base UI Compatibility Notes

When using shadcn with Base UI (not Radix), several component APIs differ. Base UI variants do not support asChild. Use these patterns instead:

Triggers: use render prop instead of asChild

// WRONG - Base UI does not support asChild
<AlertDialogTrigger asChild>
  <Button variant="ghost">Delete</Button>
</AlertDialogTrigger>

// CORRECT - use render prop
<AlertDialogTrigger
  render={<Button variant="ghost" />}
>
  Delete
</AlertDialogTrigger>

Styled links: use buttonVariants instead of <Button asChild>

import { buttonVariants } from "@/components/ui/button";
import { cn } from "@/lib/utils";

// WRONG - asChild not supported
<Button asChild variant="outline" size="sm">
  <a href={url} download>Download</a>
</Button>

// CORRECT - use buttonVariants utility
<a href={url} download className={cn(buttonVariants({ variant: "outline", size: "sm" }))}>
  Download
</a>

DropdownMenuTrigger: apply styles directly

DropdownMenuTrigger renders a button by default. Do NOT wrap it with <Button asChild> — this causes nested buttons and hydration errors.

// WRONG - causes hydration error
<DropdownMenuTrigger asChild>
  <Button variant="outline" size="icon">...</Button>
</DropdownMenuTrigger>

// CORRECT - apply styles directly
<DropdownMenuTrigger className="inline-flex items-center justify-center ...">
  ...
</DropdownMenuTrigger>

Slider onValueChange type safety

The Base UI Slider onValueChange callback may return number | number[] depending on configuration. Always guard with Array.isArray:

<Slider
  value={[currentValue]}
  => {
    const num = Array.isArray(val) ? val[0] : val;
    setValue(num);
  }}
/>

Practical Examples

Example 1: Animated Landing Page Card (React Bits)

bunx shadcn@latest add @react-bits/animated-card

import { AnimatedCard } from "@/components/ui/animated-card";

export function FeatureCard() {
  return (
    <AnimatedCard className="bg-card border border-border">
      <h3 className="text-foreground font-bold">Feature Title</h3>
      <p className="text-muted-foreground">Interactive animated card component</p>
    </AnimatedCard>
  );
}

Example 2: Audio Player for Voice Content (ElevenLabs UI)

bunx shadcn@latest add @elevenlabs-ui/audio-player

import { AudioPlayer } from "@/components/ui/audio-player";

export function VoicePreview() {
  return (
    <div className="bg-card border border-border rounded-xl p-4">
      <AudioPlayer
        src="/audio/sample.mp3"
        className="text-foreground"
      />
    </div>
  );
}

Example 3: Interactive Map (MapCN)

bunx shadcn@latest add @mapcn/map-viewer

import { MapViewer } from "@/components/ui/map-viewer";

export function LocationMap() {
  return (
    <MapViewer
      center={[-122.4194, 37.7749]}
      zoom={12}
      className="border border-border rounded-xl"
      markers={[
        { lat: 37.7749, lng: -122.4194, label: "San Francisco" }
      ]}
    />
  );
}

Mixing Components from Multiple Registries

import { Button } from "@/components/ui/button"; // Official shadcn
import { AnimatedCard } from "@/components/ui/animated-card"; // React Bits
import { AudioPlayer } from "@/components/ui/audio-player"; // ElevenLabs UI

export function RichMediaCard() {
  return (
    <AnimatedCard className="bg-card border border-border p-6">
      <h2 className="text-foreground text-2xl font-bold mb-4">Podcast Episode</h2>
      <AudioPlayer src="/episodes/latest.mp3" />
      <Button className="mt-4 bg-primary text-primary-foreground">
        Subscribe
      </Button>
    </AnimatedCard>
  );
}

Testing Checklist

• Toggle works (Light/Dark/System)
• Theme persists after page refresh
• No white flash on page load
• No hydration errors in console
• All text readable in both modes
• All borders visible in both modes
• Components from different registries work together
• Registry namespaces resolve correctly
• globals.css contains html { @apply h-dvh overscroll-none; }
• .dark block in globals.css uses monochrome grays (chroma=0) for all neutral variables